Method of preparing creosoting compositions and apparatus therefor



l,849,19&

March 15, 1932.

vS. P. MILLER METHOD OF PREPARNG CREOSOTING COMPOSITIONS AND APPARATUSTHERFOR Filed June 8. 1927 2 Sheets-Sheet www March 15, 19,32. 1,849,198

METHOD oF PREPARINGCREOSOTLNG- COMPOSITIoNs AND APPARATUS THEREFOR S. P.MILLER 2 Sheets-Sheet 2 Filed June 8. 1927 INVENTOB 72M- gaw; )[JM'ATTORNEYS hot coke-'oven gases may be cooled in a reg- Patented Mare 15,1.9.32

UNITED STATES l'PATENT OFFICE STUART PARMELEE MILLER, OF TENAFLY, NEWJERSEY, ASSIGNOR TO THE BARRETT COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW JERSEY METHOD OF PREPARING'CREOSOTING COMPOSITIONSAND APPARATUS THEREFOR Application led June 8, 1927. Serial No. 197,341.

This invention relates to improvements in the operation ofcoal-distillation plants, and more particularly coke-oven batteries, andis directed especially to the direct production of salable by-productsby such operation.

In the ordinary operation of b -product coke ovens the gases produced byt ie cokmg operation pass from the individual ovens through uptake pipesand goose-necks to a collector main common to the ovens of the battery.The coke-oven gases which leave the ovens at temperatures of from 600oto 700o C.' or higher are cooled in the collector main and in condensersconnected therewith to separate tar constituents therefrom. Theseparated coal tar is commonly shipped to tar-distillation plants whereit is subjected to distillation to produce coal-tar distillates andpitches.

One of the important products produced from coal-tar is the so-calledcoal-tar solution consisting of a mixture of coal-tar distillate withraw tar in the proportions of about eighty per cent. of distillate toabout twenty per cent. of tar. This product is used widelyfor'creosoting purposes. The preparation of thi-s product involves, asindicated, the distillation of large amounts oftar with the incidentexpense of transporting the tar to the tar-distillation plant and thecost of distillation thereof. Moreover.

' the distillation of coal tar in ordinary eX- ternally heated stillscauses a considerable of an improved product at decreased expense.

In carrying out the invention the cokeoven plant may, for the most part,be operated in theusual manner, that is to say, the

ulated manner in the collector main by sprays of ammonia liquor orammonia liquor and tar to separate from the gases some of the tarryconstituents which may be withdrawn from the collector main and utilizedin any desired manner, for example, by distillation to separate oilAconstituents therefrom and to produce pitch. The resulting partiallycooled gases can ,then be conducted through the usual cross-over main tothe condensing system in which the gases are further cooled to separateoils therefrom. These oils contain normally too high a proportion oftarry constituents to be useful as substitutes for ordinary coal-tarsolution. To reduce this proportion of tarry constituents, a part of thegases ilowingfrom the collector main to the condensing system isby-passed and subjected to cleaning to remove the tarry constituentstherefrom after which the gases are passed to the condensing` system. yBy thus by-passing and cleaning part ofthe gases, e. g., about one-thirdof the gases, the tarry constituents therein are removed and when theclean anduncleaned gases are mingled and cooled in the condensers, acomposite product suitable for use as a creosoting composition can beobtained directly. The relative proportions of the clean and uncleanedgases can be regulated readily by the application of suitable valveswhich may be adjusted from 'time to time as may be necessary to producea product suitable for use as a creosoting com; position.

The condensers employed may be of the usual wet type in which the gasesflow upwardly and counter-current to a stream of ammonia liquor which isdivided in the condenser by the provision of suitable batliing devicestherein to ensure maximum contact between the gases and the solution.The condensed oil can be withdrawn from the condensers togetherv withthe ammonia liquor and separated therefrom in a decanter provided forthat purpose. The gases escaping from the condensers can be delivered tothe usual exhauster and passed thence through'- most eiectively by theuse of an electrical precipitator such, for example, as the well knownCottrell precipitator. To ensure ef- :Eective operation thetemperatureof the collector main and of the precipitator should be carefullyregulated. The dewpoints of the y gases for the several constituentscarried therein as vapor are lower than the normal boiling points ofthese constituents and by suitable regulation of the temperature of thegases in the collector main and during recipitation, it is possible toretain the desired oil constituents in the vapor phase while the heaviertarry or pitch constituents are converted into the liquid phase in whichcondition they are separated readily by electrical precipitation. Thetemperature of the gases should, to accomplish the intended purpose, bemaintained above the dew point of the gases for the most readilycondensable oil constituent desired so that the greater proportion ofthe oils will be retained and will bey carried over with the gases fromthe collector main. The electrical precipitator should be operated atsubstantially the same temperature asthe collector main, and should beinsulated if necessary to avoid the loss of heat from the gasesundergoing precipitation. The temperature of the gases leaving thecollector main and passing through the electrical precipitator may be,for example, around 200 C., or in some cases even higher, although inother cases it may be lower, e. g., around 160 C. or 150 C., etc. Theelectrical pecipitator should beconstructed so as to' capable ofwithstanding the `temperatures to which it is subjected in the operationas described. n The operation ofan electrical precipitator consists ofpassing the gas to be treated bctween electrodes whose difference inelectrical potential is very great. Experience has shown that it is bestto use a rectified alternating current. The alternating current (theprimary) is sent through a step-up transormer to produce a highpotential current (the secondary) which is then rectified to anintermittent uni-directional current, for example, by means of a rotaryconverter. The rectified current is delivered from the converter to theelectrical precipitator at practically the potential at which it leavesthe transformer.

The electrical precipitator consists commonly of a group of verticalpipes with a. wire or rod in the center of each, the pipes beingconnected to proper headers for the intro` duction and discharge of thegases. The pipes generally constitute the positive electrodes and thewires or rods the negative electrodes.

Y The size of the pipes may vary but in general pipes of less than sixinches in diameter are not used'. Electrical precipitators with pipessix inches in diameter using secondary voltages from 35,000 to 50,000volts are satisfactory for the purpose of this invention. It isgenerally Ibest to operate with maximum potential di'erence (secondarycurrent) b etween the electrodes, this maximum being just below thebreak-down voltage at which arcing occurs.

The eliciency of the cleaning is dependent upon several variables.Satisfactory cleaning of the gas may be accom lished if the i time oftreatment is of the or er of one second although this time may be variedwidely dependingupon the character of the oil-to be recovered from thegases passing through the precipitator.v In worklng with tubes nine feetlong and six inches in diameter, for example, a gas substantially freefrom all tarry constituents has -been obtained with 'a time of treatmentof from one and onehalf to two seconds, that is to say, with a asvelocity of 6 to 4.5 feet per second. Tis has given an efficiency ofcleaning of a proximately ninety-nine per cent. If it 1s desired tocollect oils containing small amounts of tar, shorter treatment may beused, for example, a treatment of from 0.5 to one second, that is tosay, a velocity of from 18 to 9 feet per second. Since the gases aftercleaning are mingled with thev dirty gases and condensed therewith, itis not essential that the cleaning ofthe gases in the electricalprecipitator be thorough or complete. The operation can be adjustedreadily to produce the desired amount of cleaning and thus to provideupon condensation an oil product of the desired character. The tarry orpitch constituents which are separated in the electrical recipitator canbe withdrawn and utilized or any de sired purpose.

The present invention is of more or less general application to theoperation of coaldistillation plants and particularly to byproductcoke-oven plants. It may be utilized, for example, in connection withSemet- Solvay, Koppers and other coke ovens.A It will be furtherillustrated by the following more detailed description taken with theaccompanying drawings which show an apparatus embodying the inventionand adapted for the practice thereof. It is intended and will ybeunderstood that the invention is not limited to the specific details ofthe apparatus as illustrated in the drawings, in which a centre box 8.The collector main is profrom the gases.

vided with spray nozzles 9 supplied through a pipe 10 with ammonialiquor or ammonia liquor and vtar for the purpose of coollng the gasesin the collector main. The ammonia liquor and the separated tar can beWithdrawn from the centre box through a pipe 11. The gases pass from thecollector`ma1n through a cross-over main 12 to condensers 13 which, ashereinbefore indicated, may be of the ordinary or Wet type. Theseparated oil with the ammonia liquor used for coollng escapes through apipe 14 to a decanter 15 Where the oil is separated from the ammonialiquor; The oil is delivered through a pipe 16 to a storage tank 17 fromwhich it may be withdrawn as required. The ammonia liquor is withdrawnthrough-a pipe 18 and delivered to a storage tank 19 from which it maybereturned by a pump 20 to the pipe 10 and to the condensers 13 forfurther use as acoolng medium. The gases from the condensers 13 pass,through a pipe 21 to an exhauster 22 which'maintains the pressurebalance in the system and are conveyed thence through the equipment (notshown) which separates ammonia, light oils, etc.,

To accomplish the purpose of the present invention part of the gases arepassed from the collector main to the condensing system through anelectrical precipitator. In the apparatus illustrated, a by-pass 23 isprovided in the cross-over main, preferably closely adjacent to theycollector main, and valves 24, 25 and 26 are introduced in thecross-over main and in the by-passto permit regulation of theproportions of the gases which are diverted through the by-pass. Anelectrical precipitator 26 is disposed in the by-pass so that the gasespassing therethrough are subjected to cleaning by electricalprecipitation to remove tarry constituents therefrom, the' gases beingreturned thereafter to the crossover main to be mingled with the dirtygases therein and thereafter to be cooled in the condensers 13 toproduce the composite product of the operation. The electricalprecipitator comprlses a shell enclosing a number of tubes 27 which aresupported in heads 28 and 29 Within the shell. An inlet 30 near thebottom of the shell communicates with a chamber 31 which is partiallyseparated from the top section by a baile 32. An outlet 33 permits theescape of gases from the separator after the latter have passed throughthe tubes.

A lurality of electrodes 34, preferably in the orm ofA metal rods,extend through the tubes andare supported on a bus-bar 35 near the upperends of the tubes. The bus-bar 35V extends at both ends into casingsl36which enclose insulators 37 upon which the bus-bar is supported. Thehigh tension current line extends into one of the casings and isconnected with the bus-bar 35, thus supplying the necessary current fromany suitable source of uni-directional current under high tension. Thecasing of the separator is groundedl or otherwise connected to thesource of current to complete the circuit. The casing and tubes form thepositive electrode, the electrodes connected to the bus-bar beingnegative. The

ionization of the solid and liquid particles causes them to separateAfrom the -gases and condensable vapors. together with the solidparticles, run down the inner walls -o the tube into the chamber at thebottom of the precipitator and can be Withdrawn through a pipe 38. Thegases carrying condensable vapors escape from the top of theprecipitator and are delivered as hereinbefore indicated to thecross-over main 12. By adjusting the valves 24 and 25 so as to permit`approximately one-third of the gases to pass through the electricalprecipitator a suiicient proportion of the tarry constituents isseparated from the gases so that the composite oil when condensed issuitable for use as a creosoting rcomposition which is similar to, butan improvement upon, ordinary coal-tar solution. The exact proportionofthe gases passing through the electrical precipitator will be Varied,of course, to meet the conditions imposed by the operation of theparticular coke oven, that is to say, to permit more or less of thetarry constituents to pass with thev gases to the condensers as may benecessary to produce an oil having the desired characteristics. Thevalves'can be adjusted readily to meet these conditions.

The method and ap aratus as described permit the direct pro uction ofcreosoting compositions at a coke oven plant in a satisfactory andeconomical manner, utilizin existing equipment. It is particularly avantageous in that it avoids the expense oftar distillation and thelosses of oil through cracking incident to such distillation, while itgives a new and improved creosoting composition in increased yieldAdirectly from the condensing system of a coke oven plant. The

new creosoting composition, while compara- The separated liquid,

stituents incapable of distillation without decomposition by ordinarydistillation methods in externally heated stills.

It will be understood that the foregoing description is illustrative of4the invention land that various changes may be made in the form andarrangement of the apparatus and in the operation thereof withoutdeparting from the invention or sacrificing any of its advantages.

I claim:

l. The method of preparing creosoting compositions, which comprisespartially cooling hot fresh coal-distillation gases so as to separatetarry constituents therefrom, dividing the gases to form two substantialportions, subjecting one portion thereof to cleaning by electricalprecipitation While `the gases are still hot so as to separate tarrvconstituents, then combining the resulting gases' and cooling them so asto recover a composite oil product containing tar.

2. The method of preparing creosoting compositions, which comprisespartially cool'- ing hot fresh coal-distillation gases so as to separatetarry constituents therefrom, dividing the gases to form two substantialportions, subjecting onaportion thereof to cleaning by electricalprecipitation while the gases are still hot so as to separate tarryconstituents, then combining the portion of hot cleaned gases with aportion which is not 'cleaned and cooling the combined gases so as torecover a composite oil product containing tar.

3. The method of preparing creosoting compositions, which comprisescollecting hot fresh coke oven .gases from a plurality of cokel ovens ina gas collector main, subjecting them to coollng therein while theystill contain oily and tarry constituents, dividing the gases to formtwo substantial portions, separating the tar from one portion of thegases by electrical precipitation while the gases are still hot,combining the resulting gases and cooling them so as to recover acomposite oil product containing tar.

4. In a coke oven battery, the combination of a pluralit of ovens, acollector main connected there o, an electrical precipitator, acondensing system, means for passing a portion of the gases from thecollector main thru the electrical precipitator at a high itemperatureto remove entrained impurities While the gases retain oil vapors, meansfor passing the gases `from the electrical precipitator to thecondensing system and means for passing the balance of the gases fromthe collectorl main to the condensing system without going through theelectrical precipitator.

5. In a, coke oven battery, the combination of a plurality of ovens, acollector main connectedthereto, means for cooling the gases in thecollector main, an electrical precipita` tor, a condensing system, meansfor passing a portion of the gases from the collector main LegalesSTUART PARMELEE MIILER.

